Super-spreaders ARE fuelling the coronavirus pandemic: 20 per cent of sufferers are responsible for 80 per cent of transmissions, study suggests

• University of Hong Kong found 70 per cent of infected patients do not pass it on
• Vast majority (80%) of transmissions comes from a minority of people (20%) 
• Supports theory that suerspreader events are the main driver of the pandemic 
• Researchers say quashing these events will help in the fight against COVID-19 

Scientists have found more evidence that 'superspreader' events are the main driving force behind the ongoing coronavirus pandemic. 

Preliminary research from Hong Kong found that around 20 per cent of COVID-19 sufferers are highly infectious, and responsible for 80 per cent of all transmissions.

However, 70 per cent of people infected with the virus do not pass it on to anyone else.

This suggests the vast majority of infections are occurring via the same people and events. 

Preliminary research from Hong Kong found 70 per cent of people infected with the virus do not pass it on to anyone else. However, it confirmed that around 20 per cent of COVID-19 sufferers are highly infectious (file photo)

A pre-print of the research is available online but the study has not yet been peer-reviewed and scrutinised by independent experts. 

However, its data shows a clear pattern. Researchers assessed more than 1,000 infections in Hong Kong between January 23 and April 28. 

They used detailed contact tracing to determine the most likely place and time when a person became infected with the SARS-CoV-2 virus, which causes COVID-19. 

Superspreading events were found to be the main form of transmission in the city.  

'That's the picture we have so far,' Ben Cowling, study co-author, told Business Insider. 

'Superspreading events are happening more than we expected, more than what could be explained by chance. 

'The frequency of superspreading is beyond what we could have imagined.' 

The study found that 70 per cent of infected people did not pass on the disease and 20 per cent of COVID-19 patients were responsible for 80 per cent of transmissions.

The remaining ten per cent of patients were to blame for the other 20 per cent of transmissions - primarily through close contact with family and people who live or work in the same building.  

'Social exposures produced a greater number of secondary cases compared to family or work exposures,' the study authors write in their paper.  

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Choirs, gym classes and business conferences and other 'superspreader events' may be responsible for most coronavirus cases, scientists say (stock)

Superspreader events are defined by an 'R' rate far in excess of one. Under normal conditions, the R0 of SARS-CoV-2 is believed to be between two and three. 

That is to say, one person, on average, infects two to three others.  

With social distancing and other precautions, the R0 can be reduced and if it drops below one, the virus is being slowly forced out of a population. 

If it exceeds one, then the virus is becoming more prevalent.  

However, as this study proves, there is significant variation between how many people are infected by each COVID-19 positive person. 

This natural variation is called the K rate. The K number tracks the extent to which new outbreaks are caused by a few superspreading events.

Writing about his own research in a New York Times article, Professor Cowling says: '[The R0 number] doesn’t convey the vast range between how much some infected people transmit the virus and how little others do.

'This is why epidemiologists also look at a virus's dispersion factor, known as "k", which captures that range and so, too, the potential for superspreading events. 

'To simplify: The fewer the number of cases of infection responsible for all transmissions, the lower k generally is (though other factors, like the R0, also are relevant).'

The researchers say focusing on these events is key in the fight against the virus, and efforts should be made to curb superspreaders.  

The academics believe their findings apply beyond the small scope of their Hong Kong-centric study and can be applied globally. 

They cite several other pieces of research which have identified superspreader events as a primary issue in the global pandemic. 

This includes a Lancet-published study which found 80 per cent of transmissions were caused by less than a tenth of cases. 

Scientists at London School of Hygiene and Tropical Medicine said last month that choir meetings, gym classes and business conferences can be 'super-spreading' events. 

One of the best examples of this, they said, is a choir rehearsal in Washington State where 87 per cent of the 61 singers ended up with the infection.  

A groundbreaking 2005 study of SARS — which is very similar to the current coronavirus — in Singapore during the '02/'03 epidemic found that six per cent of cases accounted for 80 percent of all transmissions. While 73 percent of infected people appeared not to have spread the infection. 

The researchers said the focus of controlling the epidemic should be to limit events where super-spreaders could wreak havoc.  

Super-spreading is known to occur in care homes, hospitals and religious places - but the scientists say other unusual events can lead to clusters of cases.   

How the 80/20 rule is spreading COVID-19 - and its other impacts 

The 80/20 rule is a wide-reaching concept which stretches from medicine and epidemiology to business and mathematics. 

Medicine  

As an epidemiological concept, it states that the vast majority (around 80 per cent) of disease transmissions come from a minority (around 20 per cent) of people. 

In 2011, a scientific study found this exact trend for the transmission of malaria.  

A study from the University of Hong Kong also shows it to be a key trait of the current coronavirus pandemic.  

However, other researchers have found the ratio is potentially even more extreme. 

London School of Hygiene and Tropical Medicine researchers suggest found ten per cent of coronavirus cases accounted for 80 per cent of global transmissions.  

Business 

The same 80/20 principle is a central dogma of business. 

It is also referred to as the Pareto principle and specifies that 80 per cent of consequences come from 20 per cent of causes. 

The principle was first derived, and subsequently named, from the imbalance of land ownership in Italy.

Vilfredo Pareto noted in 1906 that 80 per cent of Italy’s land was owned by 20 per cent of the people. 

It is regularly used to illustrate the notion that not all things are equal.

For example, 80 of a firm's income may come from 20 per cent of clients of products. 

Also, 80 per cent of complaints come from around 20 per cent of customers.   

Dating 

The Pareto Principle has now been adapted to apply to almost all aspects of modern life.  

So-called relationship experts say your significant other and relationship can only provide you with a maximum of 80 per cent of your happiness. 

And, in order to be complete, a person must be able to provide the other 20 per cent themselves. 

Diet 

One diet which some people follow also makes use of the 80/20 rule. 

It states that a person will lose eight and be healthier f they eat healthy foods, 80 per cent of the time. 

The other 20 per cent of the time they are able to indulge. 

This balance is claimed to strike the right balance between progress and satisfying cravings.